Sound wave producing device



Feb. 6, 1934. MQRRISON 1,946,098

SOUND WAVE PRODUCING DEVICE Filed Sept. 19, 1951 Patented Feb. 6, 1934 UNITED STATES PATENT oFFicE 1,946,098 SOUND WAVE PRODUCING DEVICE Montford Morrison, Long Island City, N. Y.

Application September 19, 1931 Serial No. 563,803

Claims. (Cl. 179115.5)

This invention relates to a class of devices of the armature torque determines the pull on commonly known as loud speakers and is applithe sound producing diaphragm orits equivalent. cable to all classes of signaling and to other Many simple and different embodiments may related art, and relates specifically to means and be made of this invention. In fact, simpler em-,

5 methods of producing sound waves from electric bodiments may be made than the one to be 60 currents by electrically excited magnetic fields hereinafter described, but the one hereinafter co-operating with movable armatures without the described, it is believed, is best suited for puremployment of direct-current-excited magnetic poses of understanding the invention. fields and without the use of permanent magnets. In the figure, 1 is a single phase alternating 0 Among the objects of this invention are to current generator supplying a primary 2 of a 65 provide means for producing sound waves from three legged transformer 3 with input electrical electric currents in a device having all the deenergy. Transformer 3 has a secondary 4 and sirable characteristics of an electrodynamic a tertiary 5. loud speaker without the necessity of employ- For clearness in understanding the theory ining direct current for the magnetic field excitavolved, the three coils are associated by'three re- 70 tion; to provide a device of the class described sistors, 6, 7 and 8; each of which constitute the to which alternating current commonly found predominating loading characteristic in each of on power lines in practice may be used directly the individual three circuits. That is, these-refor providing the necessary magnetic field exsistors are suificiently heavy, as compared with citation; and, further, to provide a device in any other loading to substantially determine the '15 which the energy consumed in producing the character of the'loading on the transformer 3. sound waves is largely drawn from the said Under these conditions, the voltage across the magnetic field circuit with its attendant adresistor 7 is in phase with the linevoltage. The vantages. Further and other objects will be apleakage reactan'ce of the transformer 3 is such 5 parent and pointed out in the specification. that the voltage across the resistor 6 lags 60be- 80 The structure herein disclosed for converting hind the primary voltage. The voltage across single phase alternating currents to polyphase resistor 8 would also lag in phase position except alternating currents is claimed in my co-pending for the condenser 9, which is shunted across" it. application Serial No. 656,295, filed February 11, The condenser 9 is of such value as tomake the 1933. resultant voltage across it and'the resistor 8.1ead 8 In the prior art devices of the class herein the primary voltage by 60. described have employed either permanent field By reversing the assumed polarity of coils4'and magnets or electro-magnets requiring direct cur- 5 their phase relation is. changed by 180 which rent for their excitation. Difiiculty in obtainresults in the voltage across resistors 6, 7 andB ing the desired results with permanent field magbeing 120 apart, or giving a true threeephase 9Q netic devices has directed the development of voltage across these resistors. the art toward electro-magnetically excited field As will be appreciatedby those. skilled in-the devices. Such devices require considerable field art upon. further reading of this specification, energy for excitation and, further, require the the number of phases is not important in em- 40 conversion of the usual alternating current supbodying my invention and any properly pol'y- 9 ply into direct current before being used to exphased currentmay be used. cite the fields. This makes a bulky, heavy and 10 is the stator of a common induction motor, expensive device for the purpose. which, in the figure, is illustrated as athTee-phase In the present invention the applicant emmachine. The voltage of resistor 6is appliedto ployspolyphase alternating currents which are stator winding 11. The voltage across resistor 7 so combined as to produce a revolving field havis applied to stator winding 12 and thevoltage ing a constant amplitude. The constant ampliacross resistor 8 and condenser 9 is applied: to tude of this field takes the place of the constant stator winding 13. The windings-as illustrated field of the prior art devices and the structure herein are merely diagrammatic andinsulatedrfor 50 involved in the use of this field is so arranged the sake of clearness and arenotindicative ofiany that its revolving plays no detrimental role in particular type of winding used or preferred. the operation of the device, the only require- The stator windings l1, l2 and-13may be of the ment being that the armature structure be of type commonly found in inductionmotors-and, such form that the torque of the armature is as illustrated herein, represent the windings of 5 proportional to the currents therein as the value a two-pole machine. 14 represents the 'com- 310 monly called rotor of the diagrammatic induction motor illustrated but may or may not rotate in the present invention, depending upon the specific design employed.

That is, the lever arm 22 may be fixed to the windings 15 and 16 so as to oscillate as a whole with the windings under operation, or the lever arm 22 may not be fixed to the said windings but provided with sufficient looseness to slip in the manner of the prony brake, as will be understood in the art. The actual rotor windings may be fixed in slots in the rotor, in which case the rotor will tend to turn. In some cases the windings will not be fixed to the rotor proper but free to move either in the slots themselves or in the air gap of the machine, which greatly reduces the moment of inertia of the moving parts, which allows the natural period of the rotating member to have a very high value, which is desirable as will be hereinafter pointed out. In this case the torque is taken by mechanical connection to the windings and the iron core is fixed.

For clearness in the present diagrammatic embodiment in the rotor, 14 is a two phase diametrical winding, indicated by crossed coils 15 and 16, the winding is fixed to the iron core and the integral mass rotates as is common in themduction motor art.

The number of phases in the rotor is not material to the invention and two phase has been used to simplify the diagram. The terminals of coil 15 are indicated by leads 1'7 and 18 and terminals of coil 16 are indicated by leads 19 and 20. 21 is a center connection for the rotor coils.

The rotor shaft is provided with a lever arm 22, which is tied by means of .a connecting link 23 to a sound producing diaphragm 24, affixed by frame 25 with respect to so that, when the rotor 14 tends to rotate in clockwise direction, the pull on the link 23 defiects the diaphragm, the deflection being proportional to some extent upon the torque on the rotor. The restoring force of the rotor in the diagram is illustrated as being the elasticity in the diagram.

Under these conditions variations in the stalled torque of the rotor 14 produces the sound waves in diaphragm 24, as will be readily appreciated by those skilled in the art.

26 is a loading device for coils 15 and 16 and may be any device in which the loading produced in the rotor coils is proportional tothe currents or voltages of the input leads 2'7, which represents leads from an input circuit supplying currents or voltages having instantaneous values proportional to the desired instantaneous deflection of the cone or other sound wave producing device 24.

In the present embodiment the loading device 26v is represented diagrammatically as being an electron discharge device of the class described in co-pending application Serial No. 421,790, filed January 18, 1930, and which, in the figure, comprises a two-phase electron discharge tube having lead 20 connected to a segmental squirrel cage anode 28 and lead 17 connected to an opposite segmental squirrel cage anode 29. Lead 19 is connected to a segmental intermeshed anode 30 and lead 18 is connected to the corresponding opposite intermeshed anode 31. 32 is the control grid of the device and 33 represents the filament thereof which is connected to lead 21 and to a source of heating current 34, which is illustrated in the figure as being better for clearness in showing the invention,

though, in practice, a different heating means is usually employed.

35 and 36 are the leads for the input circuit which may be taken as coming from any circuit in which the current form therein represents the wave form of the sound waves to be produced on 24 and, by way of example, may be considered as coming from the amplifier circuit of, for instance, a radio receiving set.

Lead 35 is connected to grid 32 and lead 36 to the filament 33. The filament 33, being illustrated as looped, is merely indicative of its having no interruptions in its electron emitting service, adjacent to the grid, due to filament supporting members. With the described tube in conjunction with input circuit 27, it is assumed that the drop in potential around the filament 33 produces no variation in instantaneous electron emission due to change in position of the electrostatic field of the anodes with respect to the filament. This assumption is made for clearness in teaching the present invention.

As more fully disclosed in the aforementioned copending application, tube 26 produces a revolving polyphase field which is constant in form and, therefore, draws from a supply line a constant amount of electric energy, the amount of which is controlied by grid 32. That is, the energy draw of tube 26 from the rotor coils 15 and 16 is instantaneously proportional to the potential of the grid 32 under proper operating conditions.

In a high resistance wound rotor circuit the stalled torque bears a close relation to the energy consumption in the rotor conditions the torque of the ly proportional to the instantaneous value of the potential of the grid 32 so that the pull on the link 23 is instantaneously proportional to the potential value of the grid 32.

It will be observed by those skilled in the art that the energy for operating sound producing diaphragm 24 comes largely from the stator exciting oircuit of the polyphase motor 10, depending largely upon and the characteristics of the circuit 27, it being possible to design a device such that substantially all of the sound producing energy is provided from the alternating current circuit instead of being supplied by stood by those skilled in the art.

It will be appreciated that such a device in a sense actsas an amplifier itself and, therefore, can be made with proper design to function with fewer stages of audio for the same sound volume than can the devices of the prior art.

The present invention is not limited to conical, flat or any other specific form of sound wave producing member and is not limited to any specific structure of invention being, broadly, an alternating-currentfield-excited sound wave producing device in which the pull on the sound producing member is instantaneously proportional to the currents representing the sound waves and independent of the alternations of the field.

The invention is further not limited to the class of device illustrated by 26, which is merely shown as illustrative of one embodiment of my r invention.

It will be obvious to those skilled in the art that this invention also constitutes a novel general translating device subject to, for instance, embodiment as a recorder by the substitution of frequency amplification device for the element 10, the \l circuit. Under these lever arm 22 is close- 1 the design of the tube 26, 1

a recording element for the sound wave producing cone in the figure.

The patentable novelty disclosed in the single phase to polyphase transformer apparatus herein described forms the subject matter of a separate application, and, therefore, the claims hereof are directed to other elements of the invention herein set forth.

The above specification being directed to the teaching of the present invention, the nature thereof is pointed out in greater particularity in the claims hereunder.

I claim:

1. A sound Wave producing device comprising a polyphased alternating-current-field winding and an armature continuously responsive to sound modulated currents and mechanically associated with a sound wave generating surface.

2. In a sound wave producing device, means for producing an alternating field, and means magnetically associated with said field for producing sound waves responsive to sound modulated currents and independent of the point to point variations in the said field.

3. A sound wave producing device, comprising a polyphased alternating-current field-winding, an armature winding magnetically associated therewith and mechanically associated with a sound wave generating surface and adapted to react under a predetermined current excitation in proportion to the amplitude of said polyphased currents and to the amplitude thereof only at any fixed frequency thereof.

4. A sound wave producing device, comprising a polyphased alternating-current field-winding, a movable armature winding magnetically associated therewith and mechanically associated with a sound wave generating surface and a loading device electrically associated with said armature winding and adapted to load the said armature winding in accordance with instantaneous variations in a sound wave modulated current.

5. A sound wave producing device, comprising a polyphased alternating-current field winding, a movable armature having a winding magnetically associated therewith, a movable member having a sound wave producing surface and mechanically associated with said armature and means adapted to actuate said armature in ac'-, cordance with variations in sound modulated currents.

6. A sound wave producing device, comprising a polyphased induction motor provided with stator excitation, a rotor having a winding thereon and a lever arm fixed thereto and mechanically linked to an element having a sound producing surface and a loading device electrically connected to said rotor winding and adapted to load the said rotor electrically in accordance with a predetermined manner, whereby sound waves are produced. 7

'7. A sound wave producing device, comprising a rotatable membe subject to oscillation about an axis thereof, motionally responsive under said oscillation to sound modulated currents, and means for converting said rotary oscillations into corresponding approximately linear motion, said means actuating a member having a surface suitable for generating sound waves.

8. The method of producing sound waves which comprises creating an alternating electromagnetic field and causing a second electro-magnetic field inter-linked with aforesaid field to react therewith in response to currents in the latter said field and independent of the point to point variations in the first said field, and the said reactions providing energy for the production of sound waves.

9. The method of producing sound waves which comprises creating an alternating electro-magnetic field and causing a second electro-magnetic field to react with aforesaid field and with a sound wave producing member, whereby the sound waves produced are responsive to current variations in the latter said field and independent of the point to point variations in the first said field.

10. The method of producing sound waves which comprises creating a rotating electromagnetic field of constant amplitude, creating a second electro-magnetic field responsive to sound wave modulated currents and reactive with first said field, and then utilizing the physical effect of the said reaction in the production of sound waves.

MONTFORD MORRISON. 

